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AFM study of defect-induced depressions of the smectic-A/air interface

Designolle, V. and Herminghaus, S. and Pfohl, T. and Bahr, Ch. (2006) AFM study of defect-induced depressions of the smectic-A/air interface. Langmuir , 22 (1). pp. 363-368.

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Official URL: http://edoc.unibas.ch/45899/

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Abstract

The smectic-A/air interface of liquid-crystal droplets with antagonistic boundary conditions is studied by atomic force microscopy (AFM). The droplets are prepared on coated silicon wafers on which a planar alignment is preferred in contrast to the homeotropic alignment at the air interface. As a result, focal conic defects appear in the smectic-A phase causing a characteristic pattern of depressions in the droplet surface. The dimensions of the defect-induced depressions are measured by AFM as a function of temperature for two different compounds possessing a smectic-A-isotropic and a smectic-A-nematic transition. Whereas the results are independent of temperature in the smectic-A-isotropic case, reflecting the first-order nature of the transition, a pronounced temperature dependence is observed for the second compound, where the depth of the defect-induced depressions decreases continuously with increasing temperature and vanishes at the second-order transition to the nematic phase. These observations can be qualitatively explained through the behavior of the layer compressional elastic constant at the smectic-A-nematic transition.
Faculties and Departments:05 Faculty of Science > Departement Chemie > Chemie > Biophysikalische Chemie (Pfohl)
UniBasel Contributors:Pfohl, Thomas
Item Type:Article, refereed
Article Subtype:Research Article
Publisher:American Chemical Society
ISSN:0743-7463
Note:Publication type according to Uni Basel Research Database: Journal article
Identification Number:
Last Modified:19 Dec 2016 13:50
Deposited On:19 Dec 2016 13:50

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